School of Ecology and Environmental Science & Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, Yunnan University, Kunming 650091, China; Institute of Environment Sciences, Department of Biology Science, University of Quebec at Montreal, Montreal, Canada C3H 3P8.
School of Ecology and Environmental Science & Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, Yunnan University, Kunming 650091, China.
Ecotoxicol Environ Saf. 2018 Jun 15;154:311-320. doi: 10.1016/j.ecoenv.2018.02.046.
The adsorption/desorption of arsenic (As) at the sediment-water interface in lakes is the key to understanding whether As can enter the ecosystem and participate in material circulation. In this study, the concentrations of As(III), total arsenic [As(T)], sulfide, iron (Fe), and dissolved organic carbon (DOC) in overlying water were observed after the initial sulfate (SO) concentrations were increased by four gradients in the presence and absence of microbial systems. The results indicate that increased SO concentrations in overlying water triggered As desorption from sediments. Approximately 10% of the desorbed As was desorbed directly as arsenite or arsenate by competitive adsorption sites on the iron salt surface; 21% was due to the reduction of iron (hydr)oxides; and 69% was due to microbial activity, as compared with a system with no microbial activity. The intensity of microbial activity was controlled by the SO and DOC concentrations in the overlying water. In anaerobic systems, which had SO and DOC concentrations higher than 47 and 7 mg/L, respectively, microbial activity was promoted by SO and DOC; As(III) was desorbed under these indoor simulation conditions. When either the SO or DOC concentration was lower than its respective threshold of 47 or 7 mg/L, or when either of these indices was below its concentration limit, it was difficult for microorganisms to use SO and DOC to enhance their own activities. Therefore, conditions were insufficient for As desorption. The migration of As in lake sediments was dominated by microbial activity, which was co-limited by SO and DOC. The concentrations of SO and DOC in the overlying water are thus important for the prevention and control of As pollution in lakes. We recommend controlling SO and DOC concentrations as a method for controlling As inner-source pollution in lake water.
湖泊沉积物-水界面砷的吸附/解吸是理解砷是否可以进入生态系统并参与物质循环的关键。本研究在存在和不存在微生物体系的情况下，通过增加四个梯度的初始硫酸盐（SO）浓度，观察了上覆水中砷（III）、总砷[As(T)]、硫化物、铁（Fe）和溶解有机碳（DOC）的浓度。结果表明，上覆水中 SO 浓度的增加触发了沉积物中砷的解吸。约 10%的解吸砷是通过铁盐表面的竞争吸附位直接解吸为亚砷酸盐或砷酸盐；21%是由于铁（氢）氧化物的还原；69%是由于微生物活性，与没有微生物活性的系统相比。微生物活性的强度受上覆水中 SO 和 DOC 浓度的控制。在 SO 和 DOC 浓度分别高于 47 和 7mg/L 的厌氧体系中，SO 和 DOC 促进了微生物活性；在这些室内模拟条件下，解吸了 As(III)。当 SO 或 DOC 浓度低于其各自的 47 或 7mg/L 的阈值，或者当这些指标中的任何一个低于其浓度极限时，微生物难以利用 SO 和 DOC 来增强其自身的活性。因此，条件不足以进行砷解吸。砷在湖泊沉积物中的迁移主要受微生物活性的控制，而 SO 和 DOC 则对其进行共同限制。因此，上覆水中 SO 和 DOC 的浓度对于湖泊中砷污染的防治非常重要。我们建议控制 SO 和 DOC 浓度作为控制湖泊水中砷内源污染的方法。
